Lake Allison was a temporary lake in the Willamette Valley of Oregon, formed periodically by the Missoula Floods from 15,000 to 13,000 BC. The lake is the main cause for the rich and fertile soil that Willamette Valley is now recognized for.

Geologists named the lake after Oregon State University geologist Ira S. Allison. Among other things, he was the first person to identify and correlate Willamette silt soil in 1953 with soils at the former lakebed of Lake Lewis in Eastern Washington. Ira Allison also documented hundreds of non-native boulders (also known as glacial erratics), in the 1930s, which were transported down the river by the floods on icebergs and left a ring around the lower hills surrounding the Willamette Valley. The most notable of these is the Bellevue Erratic, off Highway 18, west of McMinnville.[6]